He next proceeds to say, that “a common nature pervades all the previously mentioned bodies, and one which goes and returns the same amid recurring changes.” In answer to this it is evident from what has been already said that not only does a common nature pervade those bodies which have been previously enumerated, but the heavenly bodies as well. And if this is the case, it is clear also that, according to Celsus (although I do not know whether it is according to truth), it is one nature which goes and returns the same through all bodies amid recurring changes.
It is evident also that this is the case in the opinion of those who hold that the world is to perish; while those also who hold the opposite view will endeavour to show, with out the assumption of a fifth substance, that in their judgment too it is one nature “which goes and returns the same through all bodies amid recurring changes.” And thus, even that which is perishable remains in order to undergo a change; for the matter which underlies (all things), while its properties perish, still abides, according to the opinion of those who hold it to be uncreated.
If, however, it can be shown by any arguments not to be uncreated, but to have been created for certain purposes, it is clear that it will not have the same nature of permanency which it would possess on the hypothesis of being uncreated. But it is not our object at present, in answering the charges of Celsus, to discuss these questions of natural philosophy.
Source: Against Celsus (New Advent)